Overlay mark

Abstract

An overlay mark formed on a photomask, comprising a first rectangular region, a second rectangular region, a third rectangular region, and a fourth rectangular region, each rectangular region having the same pattern configuration, a longer side of the first rectangular region and a longer side of the third rectangular region being parallel to each other, and the first and third rectangular regions have the same first pattern configuration having a first pattern element, a longer side of the second rectangular region and a longer side of the fourth rectangular region being parallel to each other, and the second and fourth rectangular regions have the same second pattern configuration having a second pattern element, the longer side of the first rectangular region being perpendicular to the longer side of the second rectangular region; wherein, the first pattern element is different from the second pattern element for allowing the second pattern configuration be chosen to align when the first pattern configuration on the substrate was damaged during process.

1. An overlay mark formed on a photomask, the overlay mark comprising:
 a first rectangular region, a second rectangular region adjacent to the first rectangular region, a third rectangular region diagonal relative to the first rectangular region and adjacent to the second rectangular region, and a fourth rectangular region diagonal relative to the second rectangular region and adjacent to both the first rectangular region and the third rectangular region, wherein the first rectangular region is parallel to the third rectangular region, of and the second rectangular region is perpendicular to the first rectangular region and parallel to the fourth rectangular region, the first rectangular region and the third rectangular region respectively have a first pattern thereon, and the second rectangular region and the fourth region respectively have thereon a second pattern which is distinct from the first pattern.